This invention relates to a rolling unit having at least two successive roll stands for rolling products such as steel bars or wire rods, in which the axis-to-axis distance between the rolls in one roll stand and those of the other roll stand is shortened so as to eliminate the need for interstand guides.
Rolling mills are known in which a plurality of roll stands are serially arranged along a pass line, and the product is rolled to a predetermined size by passing it through these roll stands. Each roll stand is equipped with a pair of rolls disposed rotatably in a housing, and the product is passed through a roll pass defined by grooves in the rolls. In the roughing and intermediate sections of the mill, the pass sequence can be "oval-round" in which oval and round roll passes are alternately disposed sequentially. Alternatively, the pass sequences can be "rhombic-square" in which rhombic and square roll passes are alternately disposed sequentially. In the finishing section of the mill, however, an oval-round pass sequence is usually employed to deliver a round product from the mill.
In the oval-round pass sequence, a roller guide is disposed at the inlet side of each round pass, so that the product can be fed in a proper orientation into the round pass and thus can be accurately rolled. In the rhombic-square pass sequence, a similar guide is also disposed at the inlet side of each square pass so as to optimize area reductions.
In the rolling mill described above, a roll parting adjustment device must inevitably be employed for adjusting the clearance or "parting" between the roll pairs so as to adjust the cross-sectional dimensions of the product passing therebetween. The roll parting adjustment device is designed to move one roll closer to or farther from the other roll, the latter roll being fixed at a predetermined position.
When the parting between the rolls is adjusted, the position of the associated roller guide disposed in the rolling unit must be adjusted correspondingly, causing an attendant loss of valuable production time. Further, since misguiding of the product by the roller guide leads to defects, maintenance of guide bearings, checking of surface flaws on the guide rollers, checking of the rolling state of the rollers, etc. must frequently be carried out. It can also be pointed out that the roller guides disposed between the respective roll stands make the structure of the rolling equipment more complicated and costly.
In such rolling mills, since housing posts for supporting the roll parting adjustment mechanisms are located on the inlet side and outlet side, the distance between the upstream roll stand and the downstream roll stand increases by the thickness of the posts. Additionally, the roller guides disposed between the roll stands also take up space, with the result that the overall length of the installation is disadvantageously increased.
A general objective of the present invention is to avoid or at least substantially mitigate the problems noted above by achieving a significant reduction in the distance between roll stands in a rolling mill.
A companion objective of the present invention is to eliminate the need for interstand guides, thereby substantially simplifying the task of adjusting the mill to accommodate different product sizes.